ARTICLES - histoire de l'odontologie médico-légale

Archaeology, forensic dentistry

Histoire de la médecine

Archaeology, forensic dentistry and mineral
structure of the dental organ: some historical cases

Xavier Riaud

If the DNA is a source of essential information in the archaeological study and the understanding of history, other elements from the dental organ belonging to the mineral structure and notably the isotopes, bring significant details. What are they ?

Body temperature

The California Institute of Technology, more commonly known as Caltech, succeeded in determining their body temperature from isotopes extracted from the teeth of dinosaurs. This was done as accurately as if it had been collected with a rectal thermometer, Therefore, the Brachiosaurus was said to have a temperature reaching 38,2 ºC and the Camarasaurus, 35,7 ºC (Lewino, 2011, p. 30).

Geographical origin

The H. L. Hunley was a submarine of the Confederate States of America which sank in 1864 during the blockade of Charleston, in the course of the American Civil War. It was only used once and was the first submarine to sink another vessel from the opposite camp. Eight men steered it and they died during the sinking. The vessel was raised in 2000. After the study of the remains, the forensic investigators started the identification of the crew. The isotopic analysis of the teeth aimed at defining the origin of each of these sailors (Hénaff-Madec, 2009).

As Rozenn Hénaff-Madec stated (2009, pp. 55-58), « the tooth develops according a well-known chronology. The developing enamel fixes elements such as carbon, oxygen, nitrogen and strontium under different isotopic shapes. Water and food bring those constituants. Therefore, isotopes develop in different concentrations according to geographic origins and diets.

Hall’s work (1967) on the 13C concentration (heavy but stable isotope of Carbon-12) in maize, Smith and Epstein’s research (1971) on the different types of C3 et C4 photosynthesis, and finally, De Niro and Epstein’s major works (1978-1981) which proved the isopotic connection of Carbon-13 / Carbon-12 with Nitrogen-15 / Nitrogen-14 are all interlocked to diet. This scientific research was the corner stone of the use of stable isotopes in archaeology and paleoanthropology. »

The same author 2009, pp. 55-58) added that : « Collagen is not the only element to use for isotopic analyses. The mineral fraction of the bones and teeth (carbonate and phosphate) is also propitious for analyses. Indeed, this mineral fraction reflects a person’s total diet whereas collagen only reveals the presence of proteins. The mineral fraction also contains isotopes of oxygen 18O and of strontium 87Sr which are elements related to a particular geographical context.

The mineral phase forms 70% of bones and of dentines, and 97% of the enamel which is mainly made up of carbonated hydroxyapatite (bioapatite). The organic component is made up of 90% of type 1 collagen. The dentine is also made up of type 1 collagen. »

Rozenn Hénaff-Madec (2009, pp. 55-58) added that: « During the growth or the renewal of bone cells, there is some sort of action coming from the osteoblast / osteoclast pair which is subjected to numerous hormonal and local factors. However, while the bone is constantly on the move, the dentine and the enamel are no longer subjected to the modification of their chemical composition once they are mature enough. Therefore, dental collagen contains more contemporary signals when developping itself. Moreover, the isotopic signals are variable from a bone sample to another as it is subjected to the variations of its renewal. »

To conclude her study, the young woman (2009, pp. 55-58) stated that : « In the case of samples taken from the molars of the Hunlay’s crew, it seemed that for four of the men, the results of the analysis showed a diet made up of wheat, rye, barley which they followed from an early age. Thus, these men were born in Europe. Among those four people, two of them had been living in the United States for a long time because the isotopic analyses carried out from their femurs showed really close results to those who were born and how lived in North America. In the four other cases, the sailors had grown up having a diet based on maize and other plants of the same group. As this type of diet was similar to that of the Americans of the time, they were subsequently born in the new world. »

In 2011, a grave was exhumed in Dorset where many Vikings had been burried (54 bodies and 51 skulls). They had been killed by local Britishmen. After examination, these men’s central incisives had been filed. The researchers assumed that those tribal mutilations aimed at frightening their enemies. The fact remains that the isotopic examinations of those particular teeth confirmed their origin. The researchers even noted that one of the cadavers came from the northern part of the arctic circle (Kennedy, 2011).

Age determination

There are several methods to determine the age of a body according to its teeth. There is Gustafson’s method (1947) who used six criteria of physiological modifications of the examined teeth according to their ageing but which implied to carry out dental inclusions and thin strips with polished sections which is not within everyone's reach. There is that of Lamendin (1988) who initially proposed a simplified version of Gustafson’s formula which only relied on three criteria and which finally, the Frenchman considered to be less reliable. Then, he defined a method which only relied on two criteria and which considered the links between the degrees of translucence, of parodontosis (except obvious pathology) with the height of the root. This is Lamendin’s formula (1990). In 1989, Drusini focused on the translucence of the radicular dentin on full teeth (Lamendin, 2006, pp. 130-131 & Riaud, 2008, p. 76). As for Hélène Martin (1996), she looked for a method of age determination from dental cement. There is also Guy Collet’s (1999) radicular chart. He studied the colour of dental roots of different ages and of different population samples. He created a benchmark chart from the results he gathered (Lamendin, 2006, pp. 130-131 & Riaud, 2008, p. 76).

In 1976 and 1977, the Mummy Of Ramses II (1314-1213 BC), the Egyptian Pharaoh, was transferred to the Musée de l'Homme in Paris for restoration. There, all the forensic examinations were carried out on the mummy. The teeth were not forgotten. Gustafson’s method of age determination allowed to ascertain that the Egyptian Pharaoh died around the age of 80, with a margin of error of more or less five years (Monier, 2006, pp. 151-157).

On November-December 1995, during the transfer of Saint Roseline’s body (1270-1329), forensic examinations were carried out. Dr Franck Domart was in charge of the odontological part. He gave up using Lamendin’s method because it implied extracting teeth. Thus, he decided to use Drusini’s method to determine the age of the relic and finally, he succeeded in ascertaining that Saint Roseline died at the age of 41 and a half with a margin of error of more or less ten years. Then, Franck Domart used the simplified method of Gustafson with which he situated the age range of the body. He stated that the age of death was between 50 and 60 years old with a margin of error of 10% (Grévin, Boyer et al., 2006).

Diet

Australopithecus afarensis, which existed between 4.100 000 and 3 000 000 years ago, has a V-shaped forward reducing jaw. The teeth share common features with current teeth. However, they differ from various aspects of specialization. The most commonly known example, popularized under the name Lucy, came from the Afar Region of Ethiopia. Its molars and premolars are large-sized. The incisors are well-developed and the canine teeth are prominent. The palate is not very deep. The mandibles are extremely robust. The jaws are projecting forward (Heim & Granat, 2001, pp. 10-37 ; Picq, 1999). The wear and tear of the teeth tells what Australopithecus afarensis used to eat. The sturdiness of the mandibular and dental bones suggests that its diet was made up of a great amount of tough vegetables. The study of the wear and tear marks brings more precision to the nature of this diet. The leaf consumption left marks on the incisors. Subsoil food which contains abrasive elements such as dust or rock grains caused the formation of little craters in the molar enamel. When studying its teeth, one knows that the southern apes of Afar consumed copiously underground plants (roots, bulbs, tubers, rhizomes, onions) and other tough nutrients such as vegetables and fruits from shrubs of the savannas. All this diet is tougher than the food found in humid forested environments which explains the sturdy face of Lucy and her own.

As for Homo neanderthalensis, they existed between 100,000 and 30,000 years ago in Europe and in the Middle East. They had forward projecting faces. The remains show that their faces have a regular and slanting shape which spreads from the nose to the zygomatic arch. The cheekbones completely disappeared. The dental archs project forward to such an extent that, if you turn the skull sideways, there is a retromolar space which separates the last molar from the mounting mandibular branch. They were flesh-eating human beings (Picq, 1999).

Profession

A macroscopic study as well as an electronic macroscopic study which scanned two lower human premolars from a Middle Neolithic individual allowed to highlight uncommon wear and tear which was unphysiological and which was due to using teeth as tools. Thanks to familiar prehistorical and ethnoarchaeological examples, scientists put forward the hypothesis that this individual used to hold the position of « crocheur » (Gilbert, 1999, pp. 31-59).

In March 2008, X-ray computed tomography was carried out on the mummy of a woman from the Coptic period which was kept in the collections of the Museum of Fine Arts in Grenoble. The study took place in the academic clinic of radiology of the Hospital A. Michallon (Janot, 2010, pp. 89-97). According to Francis Janot (2010, pp. 89-97), « (…) The woman’s coronary surfaces of the upper incisive group (11, 12, 21, 22) carried a transverse mesiodistal groove : a loss of substance which was not the simple consequence of chewing. It started from the upper left lateral incisor (22) to finish to the distal contact point of the upper right lateral incisor. From a palatine exposure, the teeth revealed that the contact surfaces which show polymorphous aspects were marked. The subsequently uncovered dentin bears a pattern of chewing due to repetitive rubbing on a hard substance which was introduced across the mouth. Therefore, the object which was introduced only spared a modest section of vestibular and palatin enamel of the crown of the upper left incisor. Moreover, parallel striae which were horizontal, one on the top of the other, were identified on the vestibular side of the left canine. They were obviously due to the repetitive introduction of the same object

The signs of dental anatomy which were noticed showed the interposition movement of an object between the teeth which started from the left side of the denture (from 22). The vestibular side of the canine (23) played the role of guide. Therefore, it is possible to assert that this woman was left-handed. » The same author (2010, pp. 89-97) maintained that : « The functional movement which was repeated thousands of times was undisputably due to the position hold by the deceased. Therefore, it is possible to recreate the movement that she always did. The polymorphous wear and tear identified on the upper incisive group were caused by a mandibular functional back and forth movement which is the counterpart of the manual oscillatory movement of the left hand and which also created a back and forth movement to result in a dilaceration of the root fibres. The vestibular side of 23 played the role of support while the crown of 22 played the role of positioning guide. Moreover, the maximal wear and tear of the occlusal surfaces of the right incisive group (11, 12) was caused to the muscular masseter activity due to the multiple forces carried out during the dilaceration of the fibres. The muscular activity shaped the external side of the right mounting mandibular branch and caused maximal pressure on the bone area of the lower insertion of the muscle at the mandibular angle level. The exostosis (or enthesis) noticed on the goniac angle was a direct consequence. It was the bone answer to the repeated pressure throughout the professional activity of the deceased of Grenoble. Naturally, the whole movement led to abundant salivation. »

Francis Janot (2010, pp. 89-97) was convinced that : « Our goal now is to find the object which caused such abrasion. Several hypotheses can be ventured : a musical activity, some work involving basket-making or ropes, weaving work or leatherwork as well as bruxism. Unfortunately, none of the marks caused by each of those activities corresponded to those noticed on the deceased of Grenoble. Howevern this forensic mark has a parallel in the African statuary. Indeed, the interposition movement of a root was recognized on wood statuettes of chiefs and soothsayer of the kôngo/vili and kôngo/yombe ethnies of the Republic of the Congo. With a movement of fibre dilaceration of the root - munkwisa, the extracted juice has hallucinogenic virtues which exacerbate the powers of perceptiveness and vision. Pharmacological studies showed that the bark of this shrub contains a powerful alkaloid: the ibogaine which stimulates the central nervous system. The consumed dose leads to hallucinations, tremblings and convulsions. A mind reading activity? The anatomical signs which were put into light in this article invite us to research more on the left aside topic concerning the members of the religious staff in charge of oracular, oral and written matters from the New Empire in Egypt. (…) From then on, the ancient Egyptian from the Museum of Fine Arts in Grenoble could bear the revealing mark of perceptiveness on her dental organ. »

To conclude, it seems necessary to recall that the teeth are rootproof and therefore, they constitute extraordinary forensic tools as well as a great source of information which, if they are used appropriately, can turn out to be an almost unfailing source.